As one of these types of cell units, a single cell of a fuel cell is disclosed in Japanese Patent No. 4432518. The single cell of a fuel cell disclosed in Japanese Patent No. 4432518 includes a membrane electrode assembly having a fuel gas channel and an oxidant gas channel formed of a concave-convex shape in a region contributing to power generation, a first separator disposed on one surface of the membrane electrode assembly, at least a surface of the first separator on the side of the disposition being flat, and a second separator disposed on the other surface of the membrane electrode assembly, at least a surface of the second separator on the side of the disposition being flat.
Moreover, the single cell of a fuel cell further includes a wave-plate cooling plate provided in contact with any one of the first separator and the second separator and having a refrigerant channel (cooling fluid passage channel) for allowing flow of a refrigerant, and a third separator disposed on the cooling plate.